This huge tree is called the "Castaño Santo de Istan" (which is Spanish for "Sacred Chestnut of Istan").
It is located near the city of Marbella in Southern Spain. It is a bit off the beaten path but if you know where it is you can drive (on a rough dirt road) to within about 150 meters of the tree.
From the start of the dirt road it takes about an hour of driving to get there. (you can make it a lot faster if you go up with an Quad)
More trees in this blog...
Indian Bean tree